The sun is a clean, renewable source of energy. One of the effective usages of the sun's energy is concentrating its light on a target via reflective (mirrors) or refractive (lens) concentrators. Sunlight can be concentrated using reflecting mirrors, refraction (lens), parabolic mirror or lens, one big or large number of smaller ones, on a slab, or on double slabs, tiltable, moveable, or with rotation. The target can be a solar cell, water heating reservoir or pipe, fuel cell reactor, photosynthesis element, etc. Power generation for under 1.7 cents/kW·hr could be produced without a toll on the environment.
In order to collect more energy, it is advantageous to keep the alpha (α) to a small value, even when the sun is moving, as shown in FIG. 1. This often requires aligning the vertical axis of the reflective or refractive elements toward the sun, such as tilting or moving those elements, when the sun moves.
The following types of concentrators are commonly used to maximize the collected sunlight energy:                1. Reflective or refractive element (panel/surface/plate/dish).        2. Array of small parabolic reflective or refractive elements on a flat-panel (dish).        3. Array of small flat reflective or refractive elements on a parabolic-panel (dish).        
All the above panels or dishes usually have tracking systems that track the sun and point the dish toward the sun. The above mentioned concentrators suffer from the fact that large and heavy panels (dishes) need to move constantly to track the sun. Such movement requires electric motors and a gearbox, which consume power and are prone to failure.